Zone isolation system with integral annular flow control valve

ABSTRACT

A zone isolation system comprising an isolation flow path arranged radially outwardly with respect to an internal bore of a production tubing. An isolation valve assembly is arranged in the isolation flow path. The isolation flow path is fluidly connected to a screen flow path defined by the annular space between a filtering assembly and a basepipe. The isolation flow path may traverse one or more zones and can extend to the wellhead, connecting to an isolation pump. The basepipe may further comprise an inflow control device such as a sliding sleeve.

BACKGROUND

A typical multizone well, requiring selective production of at least onezone is generally configured where one or more upper zones have acontrol valve assembly, such as a mechanical sliding sleeve locatedinternal to the basepipe, whereby the mechanical sliding sleeve controlscirculating flow during the gravel packing operation. Due to thenecessity to locate the mechanical sliding sleeve on a concentrictubular internal to the basepipe, the resulting internal diameterbecomes small, inhibiting production flow. Accordingly, the industry isreceptive to advancements in zone isolation technology, particularlysystems that preserve the internal diameter of the production tubingwhile maintaining control of production flow in independent zones.

SUMMARY

Disclosed herein is an isolation system for a subsurface borehole havingmultiple production zones comprising a tubular string including abasepipe, the tubular string comprising an internal bore. An isolationflow path arranged radially outwardly of the internal bore is connectedto a screen flow path arranged radially outwardly of the basepipe. Thefluid connection between the screen flow path and the isolation flowpath is controlled by an isolation valve assembly.

Also disclosed herein is an isolation system for a well having multipleproduction zones, comprising a filtering assembly arranged on abasepipe, an annular space between the filtering assembly and thebasepipe defining a screen flow path. The system further comprises atubular coupled to the basepipe. The tubular has an isolation flow patharranged radially outwardly of an internal bore of the tubular. Thetubular is arranged relative to the basepipe such that the isolationflow path is in fluid communication with the screen flow path. Anisolation valve assembly is arranged in the isolation flow path.

Also disclosed herein is an isolation system for a well having one ormore production zones, comprising a basepipe arranged in a tubing stringadjacent to a production zone. A filtering assembly is arranged on thebasepipe, defining at least one screen flow path between the filteringassembly and the base pipe. A flow control device is arranged on thebasepipe to permit fluid communication between the production zone andan internal bore of the base pipe. A production tubing is also arrangedin the tubing string having at least one isolation flow path. Theisolation flow path is fluidly connected to the at least one screen flowpath and is isolated from an internal bore of the production tubing. Anisolation valve assembly is arranged in the isolation flow path.

Also disclosed herein is an isolation valve assembly having a firstopening connected to a first flow path and a second opening connected toa second flow path, the second flow path located radially inwardlyrelative to the first flow path. The isolation valve assembly comprisesa first piston with a first flanged section configured to obstruct fluidcommunication between the first opening and the second opening when thefirst piston is in a first position and to permit fluid communicationwhen the first piston is in a second position. The first piston alsocomprises a second flanged section. A second piston is arranged betweenthe first flanged section and the second flanged section of the firstpiston, with a biasing member located between the second piston and thesecond flanged section. The isolation valve assembly further includesone or more locking dogs, configured to have a first position in whichthe one or more locking dogs restrict the movement of the first pistonwhile not restricting the movement of the second piston, and a secondposition in which the one or more locking dogs restrict the movement ofthe second piston while not restricting the movement of the firstpiston.

Also disclosed herein is an isolation system for a subsurface boreholecomprising a tubular string including a basepipe. A screen flow path islocated radially outwardly of the basepipe. The screen flow path,located radially outwardly of an internal bore of the tubular string, isfluidly connected to an isolation flow path by an isolation valveassembly. The isolation valve assembly is configured having two or morepositions, including a first position in which the isolation valveassembly is arranged to fluidly connect the screen flow path to theinternal bore, and a second position in which the isolation valveassembly is arranged to fluidly connect the screen flow path to theisolation flow path.

Also disclosed herein is an isolation system for a subsurface boreholehaving multiple production zones, comprising an outer tubing string andan inner tubing string. The outer tubing string spans two or more zoneswhile the inner tubing string spans one or more zones. The outer tubingstring includes at least one circular flow valve associated with each ofthe production zones. The inner tubing also includes one or more flowports in at least one of the production zones. One or more sealing subsare arranged in the annular space between the inner tubing string andthe outer tubing string. One or more shifting tools are arranged on theinner tubing for arming the one or more circular flow valves, the armedcircular flow valves being operable by hydraulic pressure when so armed.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is a schematic of a zone isolation system according to oneembodiment;

FIGS. 2A and 2B are quarter-sectional views of a zone isolation systemaccording to another embodiment;

FIG. 3 is an illustration of a base pipe and screen assembly of the zoneisolation system illustrated in FIGS. 2A and 2B;

FIGS. 4A-C are quarter-sectional views of various positions of anisolation valve assembly according to one embodiment;

FIG. 5 is a schematic of an isolation valve assembly according toanother embodiment;

FIG. 6 is a schematic of an isolation valve assembly according toanother embodiment; and

FIG. 7 is a partially sectioned view of a zone isolation system having aproduction string run through one or more production zones according toanother embodiment.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures. It is to be understoodthat other embodiments may be utilized and changes may be made withoutdeparting from the scope of the present disclosure. In particular, thedisclosure provides various examples related to a zone isolation systemfor use in well operations, whereas the advantages of the presentdisclosure as applied in a related field would be apparent to one havingordinary skill in the art and are considered to be within the scope ofthe present invention.

FIG. 1 illustrates one embodiment of a zone isolation system 1 of thepresent disclosure, which is installed with a tubing string 2 in awellbore 3 having one or more production zones 4. The zone isolationsystem 1 will be described with respect to a first production zone 4,but as discussed below, may be any one of a plurality of productionzones, without regard to any ordering of zones within the well. Thewellbore 3 may further comprise a casing or liner surrounding all or aportion of the length of the tubing string 2.

A basepipe 5 and filtering assembly 6 are arranged adjacent to theproduction zone 4 between one or more packing elements 7, 8. An inflowcontrol device such as a sliding sleeve 9 is arranged on the basepipe 5,the sliding sleeve 9 having one or more openings 10. The basepipe 5further comprises one or more inflow ports 11 which allow fluidcommunication between the production zone 4 and the internal bore 12 ofthe tubing string 2. The sliding sleeve 9 is configured to traverse inan axial direction such that the one or more openings 10 in the slidingsleeve can be aligned with the one or more inflow ports 11 of thebasepipe 5. The sliding sleeve 9 may be pressure-activated and/ortool-shiftable, as desired, to support gravel-packing, fracking, fluidproduction, and other operations.

FIGS. 2A and 2B provide detailed illustration of adjacent portions ofthe tubing string 2. The filtering assembly 6, shown in more detail inFIG. 2B, comprises a wire wrap 13 that overlays a series of ribs 14,which extend in parallel in an axial direction along the basepipe 5 toend ring 15. The ribs 14 may extend between a portion of the end ring 15and the basepipe 5. As shown in FIG. 3, the ribs 14 maintain a spacebetween the wire wrap 13 and the basepipe 5, defining a number of screenflow paths 16, which may extend into the end ring 15.

One end of the end ring 15, opposite the filtering assembly 6, forms aflow-through seal bore 17. The flow-through seal bore 17 is an annularspace connecting the basepipe 5 and the screen flow paths 16 withanother tubular, such as a coupling 18, having an isolation flow path 19therein. The flow-through seal bore 17 is associated with one or moresealing elements 20 that maintain the isolation of the isolation flowpath 19 from the internal bore 12 of the tubing string 2.

The coupling 18 is further connected to a production tubing 21, whichcontinues the isolation flow path 19. As shown in FIG. 1, the isolationflow path 19 traverses the packing element 7 which isolates theproduction zone 4 from the rest of the formation. The isolation flowpath 19 may further traverse other packing elements and extend to thewellhead where the isolation flow path may be connected to an isolationpump 22, used to pump fluid from or into the isolation flow path, as maybe desired. The isolation flow path 19 may comprise one or more axiallyextending channels, an isolation space, or any other configuration asmay be apparent to one with skill in the art.

The isolation flow path 19 of the zone isolation system 1 discussedherein enables flow control over one or more production zones inisolation without requiring an isolation pipe. Fluid flow through theisolation flow path 19 is further controlled by an isolation flowcontrol device, such as isolation valve assembly 23 shown in FIG. 2A.The isolation valve assembly 23 may comprise a pressure-activated and/ortool-shiftable valve or group of valves, as desired, to support variouswell functions. The isolation valve assembly 23 illustrated in FIG. 2Amay be an annular valve assembly comprising a mandrel 24 having one ormore valve ports 25. The mandrel 24 is configured to displace axiallyupon the application of pressure, via chamber 26, or by using a tool,via tool interface 27.

Referring again to FIG. 1, the isolation valve assembly 23 may be usedto fluidly connect the production zone 4 with other production zones orwith the isolation pump 22 or another device at the well head.Alternatively, the isolation valve assembly 23 may be used in connectionwith additional inflow control devices such as a second sliding sleeve(not shown) arranged internal to the production tubing 21 and separatedfrom the production zone 4 by the isolation valve assembly 23.

As shown in FIG. 1, the isolation flow path 19 is formed in a radiallyoutward portion of the tubular string 2 that is fluidly connected to ascreen flow path 16 between the filtering assembly 6 and the basepipe 5.The isolation flow path 19 may be provided in a number of configurationsto emphasize desired attributes of the present disclosure. For example,while the isolation flow path 19 could be configured as an annular spacebetween two concentric tubulars, the isolation flow path 19 may also beformed as one or more passages in a radially outward portion of a singletubular. The isolation flow path 19 may be configured to provide a flowpath that is isolated from the internal bore 12 of the tubing string 2while having a negligible impact on the overall diameter of the internalbore 12. In one embodiment, portions of the isolation flow path 19 maycomprise an annulus or a portion of an annulus formed between an innerwall and an outer wall of a production tubing 21. Alternatively, theisolation flow path 19 may comprise an annular space between aproduction tubing 21 and a blank pipe or other external tubular thatexists between the production tubing 21 and the wellbore or casingthereof.

In some embodiments, the operation of the isolation valve assembly 23 iscoordinated with the operation of the sliding sleeve 9 arranged with thebasepipe 5. For example, the tool interface 27 may be connected to boththe isolation valve assembly 23 and the sliding sleeve 9. In a furtherembodiment, the isolation valve assembly 23 and the sliding sleeve 9 areoperatively constrained such that only one valve may be open at anygiven time.

The isolation valve assembly 23 of the embodiments illustrated in FIGS.1 and 2A is shown as being integrated into the production tubing 21 ofthe tubing string 2. Other embodiments of the present disclosure mayfurther arrange the isolation valve assembly in any number ofconfigurations relative to the basepipe 5 and other features of the zoneisolation system 1, such as uphole, downhole, in close proximity to thebasepipe 5, or near the wellhead.

FIGS. 4A-C illustrate another embodiment of the isolation system of thepresent disclosure, in which the isolation valve assembly 23 comprises acircular flow valve 28 for controlling circular flow between an annularvolume and the radially adjacent internal bore 12. The circular flowvalve 28 fluidly connects or disconnects the screen flow path 16 withthe internal bore 12 through one or more radial flow ports 29 on theinternal diameter of the isolation valve assembly 23. A seal piston 30is arranged to isolate the radial flow ports 29 when in a closedposition, as shown in FIGS. 4A and 4B.

Referring to FIG. 4A, which shows the circular flow valve 28 in a closedposition, the seal piston 30 further comprises a first flanged section31 and a second flanged section 32. The first flanged section 31 isconfigured to interrupt the fluid communication between the screen flowpath 16 and the internal bore 12 and includes one or more sealingelements 33. The second flanged section 32 is configured to support aspring 34 or other biasing member. The circular flow valve 28 furthercomprises a spring piston 35 that is used to actuate the seal piston 30.The spring piston 35 includes one or more collet fingers 36 that areinitially held in place, for example, by a support ring 37. The colletfingers 36 extend into a housing 38 and engage the support ring 37adjacent to a cavity 39. The spring 34 is arranged in a spring chamber40, formed between the spring piston 35 and the second flanged section32 of the seal piston 30. The housing 38 further includes one or morelocking dogs 41 arranged in a recess 42 of the housing 38. As shown inFIG. 4A, the locking dogs 41 are arranged to prevent the movement of theseal piston 30.

As shown in FIG. 4B, the circular flow valve 28 is made operable bydisengaging the support ring 37 from the collet fingers 36 so that thespring piston 35 can translate. This is done, for example, by using atool to move the support ring 37 in an axial direction, for example,beyond the distal ends of the collet fingers 36, the distal ends beingthe location on the collet fingers that is furthest from the springpiston 35. The cavity 39 is arranged in the housing 38 to allow thecollet fingers 36 to deflect in a radial direction and disengage fromthe support ring 37. With the support ring 37 removed from the colletfingers 36, the spring piston 35 is influenced by a difference inpressure between the internal bore 12 and the spring chamber 40. Inparticular, when the fluid pressure in the internal bore 12 is greaterthan the fluid pressure in the spring chamber 40, the spring piston 35will be forced against the spring 34.

When the difference in pressure is great enough to displace the springpiston 35 such that the collet fingers 36 are no longer radiallyadjacent to the locking dogs 41, the locking dogs are free to move in aradial direction, thereby releasing the seal piston 30 and allowing itto move in an axial direction. This arrangement is illustrated in FIG.4C. In this position, the locking dogs 41 may also prevent the springpiston 35 from returning to its original position. With the locking dogs41 disengaged from the seal piston 30, the compressed spring 34 causesthe seal piston 30 to move in an axial direction from a first positionto a second position in which the radial flow ports 29 are no longerobstructed, thereby placing the internal bore 12 in fluid communicationwith the one or more screen flow paths or isolation paths 19. Thecircular flow valve 28 may further comprise one or more stops 43 forlimiting the range of motion of the seal piston 30 and/or the springpiston 35, in one or more directions.

The circular flow valve 28 depicted in FIGS. 4A-C may be configured toopen when production from a particular zone is desired. In someembodiments, the circular flow valve 28 may include a tool or hydraulicdevice that will return the seal piston 30, the spring piston 35, thelocking dogs 41, or other elements to their original positions shown inFIG. 4A.

In another embodiment of the present disclosure, shown in FIG. 5, theisolation valve assembly 23 may combine the functionality of an firstvalve component 44, controlling axially directed flow through an annularspace, and a second valve component 45, controlling radially directedflow. The first valve component 44 may be configured, for example,having an axially moving mandrel and one or more first valve componentports 46, similar to the valve depicted in FIGS. 2A and 2B. In theembodiment illustrated in FIG. 5, the second valve component 45 islocated between the first valve component 44 and the screen flow path16. The second valve component 45 allows fluid connection between thescreen flow path 16 and the internal bore 12, similar to the valve shownin FIGS. 4A-4C. Alternatively, as shown in FIG. 4, a second tubularstring 48 may be arranged in the internal bore.

As shown in FIG. 5, the second valve component may comprise one or moresecond valve component ports 48 which are opened and closed by themovement of second valve component sleeve 49. The second valve componentsleeve 49 may be controlled by hydraulic pressure or by toolintervention, as may be useful for isolation of the various productionzones. FIG. 4 depicts the second valve component sleeve 49 extendinginto a radial sleeve chamber 50, by which the movement of the secondvalve component sleeve 49 may be controlled by differential hydraulicpressure.

The first valve component 44 and the second valve component 45 may beoperated as part of a control scheme to isolate any number of productionzones without limit into two or more production flows. In a furtherembodiment, shown in FIG. 6, the functionality of the first valvecomponent 44 and the second valve component 45 are combined into anisolation control valve 51. The isolation control valve 51 allows theisolation valve assembly 23 to selectively connect the screen flow path16 to either the isolation flow path 19 or to the internal bore 12 ofthe tubing string. The isolation control valve 51 depicted in FIG. 6comprises an isolation control mandrel 52 that extends into an isolationcontrol chamber 53. The isolation control mandrel 52 is configured tointerface with one or more second valve component ports 47 and with oneor more first valve component ports 46. The isolation control mandrel 52may be arranged to radially traverse a space between the second valvecomponent ports 47 and the first valve component ports 46, as shown, orthe isolation control valve 51 may be arranged in any otherconfiguration, including those that would allow for a substantiallycylindrical isolation control mandrel 52. One or more openings 54 may beformed in the isolation control mandrel 52 in order to align with thefirst valve component ports 46, as shown, or with the second valvecomponent ports 47.

In operation the isolation control valve 51 is configured to have two ormore positions, including, for example, a position in which the screenflow path 16 is not fluidly connected to the isolation flow path 19 orto the internal bore, a position in which the isolation valve assembly23 is configured to fluidly connect the screen flow path 16 to theinternal bore only, a position in which the isolation valve assembly 23is configured to fluidly connect the screen flow path 16 with theisolation flow path 19, and a position in which the isolation valveassembly 23 is configured to fluidly connect the screen flow path 16with both the isolation flow path 19 and the internal bore. In theisolation control valve 51 of FIG. 6, each of these positions isachieved by axial displacement of the isolation control mandrel 52. Asmay be appreciated by those in the art, the relative positions of thevarious ports and openings may be selected to operate the isolationcontrol valve 51 in a specific manner as desired. Referring to FIGS. 4and 5, the functionality of the isolation control valve 51 may also beachieved by coupling the operation of the first valve component 44 withthe second valve component 45. In each configuration, the variousoperations of the valve may be controlled by either pressure or by toolintervention in order to isolation the various production zones asdesired.

Another embodiment of the present disclosure, shown in FIG. 7, comprisesa production string 55 run internal to the tubing string 2 and adjacentto two or more production zones 4. The production string 55 may be used,for example, with the circular flow valve 28 depicted in FIGS. 4A-C toisolate the two or more production zones 4 into two or more isolatedproduction flows that may comingle production from selected productionzones 4. Each production zone 4 is isolated, for example by gravel pack,and includes one or more screen assemblies 56 and one or more circularflow valves 28, each of which is included in the radially outward tubingstring 2. The production string 55 separates a production string bore 57from an annular space 58 located between the production string 55 andthe tubing string 2.

One or more shifting tools 59 are run provided with the productionstring 55. The one or more shifting tools 59 are used to arm theindividual isolation valve assemblies 23, for example by shifting theassociated support ring 37 (See FIGS. 4A-C). The one or more shiftingtools 59 may comprise a single tool at the distal end of the productionstring 55, as indicated in FIG. 7, used to arm each of the isolationvalve assemblies 23 upon insertion of the production string 55 in asingle pass. Alternatively, the one or more shifting tools 59 maycomprise a plurality of tools arranged adjacent to each of the isolationvalve assemblies 23 for further control of the circular flow valves. Theproduction string 55 also comprises one or more sealing subs 60 toisolate two or more of the production zones 4. The sealing subs 60 maycomprise valves or ports to communicate the annular space 58 associatedwith one production zone 4 with the annular space 58 associated withanother production zone 4.

Within one or more of the production zones 4, the production string 55further comprises one or more production openings 61, such as perforatedpups, ported subs, sliding sleeve devices, or the like. Flow between theannular space 58 and the production string bore 57 may be controlled byselectively opening or closing the production openings 61. In someembodiments, the production openings 61 are opened or closed by usinghydraulically operated sleeves (not shown). In these embodiments, thefluid connection between the production zones 4 and the annular space58, such as through a sliding sleeve on the basepipe, would be operableby shifting tool, but not by hydraulic pressure. In this configuration,the isolation of various flows is distinct from the control of access toindividual zones.

The production string 55 of this embodiment allows the circular flowvalves 28 in individual production zones 4 to be selectively openedand/or closed to customize the grouping of the isolated productionflows. Alternatively, the production string 55 may be used in connectionwith the isolation control valve 51 of FIG. 6, or with screen assembliesequipped with a sleeve for controlling radial flow, or with similarlyconfigured systems.

The terms “inflow,” “uphole,” and other words and phrases suggestingorientation are provided herein as exemplary and do not constrain thepresent disclosure to embodiments in which the orientation matches thoseof the examples given. For example, while the sliding sleeve 9 isdescribed above as an “inflow control device,” the feature is equallysuited to permitting circulating flow in gravel packing and otheroperations in which the direction of the fluid flow is radiallyoutwardly.

While the invention has been described with reference to an exemplaryembodiment or embodiments, it will be understood by those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Also, in the drawings andthe description, there have been disclosed exemplary embodiments of theinvention and, although specific terms may have been employed, they areunless otherwise stated used in a generic and descriptive sense only andnot for purposes of limitation, the scope of the invention therefore notbeing so limited. Moreover, the use of the terms first, second, etc., donot denote any order or importance, but rather the terms first, second,etc. are used to distinguish one element from another. Furthermore, theuse of the terms a, an, etc. do not denote a limitation of quantity, butrather denote the presence of at least one of the referenced item.

1. An isolation system for a subsurface borehole having multipleproduction zones, comprising: a tubular string having an internal bore,the tubular string comprising a basepipe; an isolation flow patharranged radially outwardly of the internal bore; and an isolation valveassembly arranged in the isolation flow path, the isolation valveassembly arranged to fluidly connect the isolation flow path to a screenflow path, the screen flow path comprising a volume arranged radiallyoutwardly of the basepipe.
 2. The isolation system of claim 1, furthercomprising an inflow control device for fluidly connecting the isolationflow path to the internal bore.
 3. The isolation system of claim 2, theisolation valve assembly being operably coupled to the inflow controldevice.
 4. The isolation system of claim 1, the isolation flow pathtraversing at least one packing element.
 5. An isolation system for awell having multiple production zones, comprising: a filtering assemblyarranged on a basepipe, an annular space between the filtering assemblyand the basepipe defining a screen flow path; a tubular having anisolation flow path formed therein, the tubular being coupled to thebasepipe such that the isolation flow path is in fluid communicationwith the screen flow path; and an isolation valve assembly arranged inthe isolation flow path.
 6. The isolation system of claim 5, theisolation flow path comprising one or more axially extending channels.7. The isolation system of claim 5, further comprising a flow controldevice configured to control fluid communication between the productionzone and an internal bore of the base pipe.
 8. The isolation system ofclaim 5, the isolation valve assembly being configured to selectivelyopen and close by using a tool or hydraulic pressure.
 9. The isolationsystem of claim 5, the isolation valve assembly being operably coupledto the flow control device
 10. The isolation system of claim 5, theisolation flow path traversing at least one packing element.
 11. Theisolation system of claim 5, the isolation flow path extending to awellhead.
 12. The isolation system of claim 5, the isolation flow pathconnected to an isolation pump.
 13. An isolation system for a wellhaving one or more production zones, comprising: a basepipe arranged ina tubing string adjacent to a production zone; a filtering assemblyarranged on the basepipe, defining at least one screen flow path betweenthe filtering assembly and the base pipe; a flow control deviceconfigured to permit fluid communication between the production zone andan internal bore of the base pipe; at least one isolation flow patharranged in the tubing string and fluidly connected to the at least onescreen flow path, the isolation flow path being isolated from aninternal bore of the tubing string; and an isolation valve assemblyarranged in the isolation flow path.
 14. The isolation system of claim13, the isolation valve assembly being configured to selectively openand close by using a tool or hydraulic pressure.
 15. The isolationsystem of claim 13, the isolation valve assembly being operably coupledto the flow control device
 16. The isolation system of claim 13, theisolation flow path traversing at least one packing element.
 17. Theisolation system of claim 13, the isolation flow path extending to awellhead.
 18. The isolation system of claim 13, the isolation flow pathconnected to an isolation pump.
 19. A isolation valve assembly,comprising: a first opening connected to a first flow path; a secondopening connected to a second flow path, the second flow path locatedradially inwardly relative to the first flow path; a first pistoncomprising a first flanged section and a second flanged section, thefirst piston having a first position in which the first flanged sectionobstructs fluid communication between the first opening and the secondopening and a second position in which the first flanged section doesnot obstruct fluid communication between the first opening and thesecond opening; a second piston located between the first flangedsection and the second flanged section of the first piston; a biasingmember located between the second piston and the second flanged section;and one or more locking dogs, the locking dogs having a first positionin which the one or more locking dogs restrict the movement of the firstpiston while not restricting the movement of the second piston, and asecond position in which the one or more locking dogs restrict themovement of the second piston while not restricting the movement of thefirst piston.
 20. The isolation valve assembly of claim 19, furthercomprising a support ring, the second piston further comprising one ormore collet fingers configured to engage the support ring.
 21. Theisolation valve assembly of claim 19, the seal piston further comprisingat least one seal;
 22. The isolation valve assembly of claim 19, thefirst opening connected to a screen flow path.
 23. An isolation systemfor a subsurface borehole having multiple production zones, comprising:a tubular string having an internal bore, the tubular string comprisinga basepipe; a screen flow path arranged radially outwardly of thebasepipe; an isolation flow path arranged radially outwardly of thetubular string; and an isolation valve assembly arranged connected tothe isolation flow path and the screen flow path, the isolation valveassembly having two or more positions, including a first position inwhich the isolation valve assembly is arranged to fluidly connect thescreen flow path to the internal bore, and a second position in whichthe isolation valve assembly is arranged to fluidly connect the screenflow path to the isolation flow path.
 24. The isolation system of claim23 the isolation valve assembly having a third position in which theisolation valve assembly is arranged to fluidly connect the screen flowpath to both the internal bore and the isolation flow path.
 25. Theisolation system of claim 23, the isolation flow path traversing atleast one packing element.
 26. The isolation system of claim 23, theisolation valve assembly comprising a first valve component, configuredto selectively control fluid flow in an axial direction, and a secondvalve component, configured to selectively control fluid flow in aradial direction.
 27. An isolation system for a subsurface boreholehaving multiple production zones, comprising: an outer tubing stringspanning two or more production zones, the outer tubing stringcomprising one or more circular flow valves in each of the two or moreproduction zones; an inner tubing string spanning one or more productionzones, the inner tubing string having one or more flow ports located inat least one of the one or more production zones, the inner tubing andthe outer tubing forming an annular space therebetween; one or moresealing subs arranged in the annular space; at least one shifting toolarranged on the inner tubing for arming the one or more circular flowvalves, the armed circular flow valves being operable by hydraulicpressure.
 28. The system of claim 27, the one or more sealing subscomprising an second flow valve configured to selectively control fluidflow in an axial direction.
 29. The system of claim 27, at least one ofthe flow ports of the inner tubing comprising a flow control device forconnecting an internal bore of the inner tubing with an annular space,the flow control device being hydraulically operated.